Working from home - in Cambodia. Implications to Ltd company?

[WTFH]

It's worth considering that if the client is led to believe that you are in the UK, then they may want to have meetings more frequently, etc.
And even if they are aware that you aren't in the UK, they still won't pay for your flights, or for the time off to recover from jet lag.

There's a big difference between going on holiday to a country and going there to work. And if you're going because you think it will be cheaper, make sure you've considered all the costs.

[Epiphone]

Not sure about Vietnam and Cambodia but leaving and re-entering Thailand every 6-8 weeks will catch Immigration's attention. They're not keen on visa runs these days.